Question

First pipe can fill a tank in 10 minutes. Second pipe can fill the same tank in 20
minutes. A third pipe can empty the same tank in 12 hours. If the tank is empty
and all three pipes are open in how many minutes will the tank fill?​

Answer 1

Step-by-step explanation:

Pipe A started the sequence of filling alternately, then at the end of two hours, the two pipes together would have filled 1/40 + 1/120 = 1/30 th of the tank in an hour. Or the cistern will fill in 30 hours